Chapter 9 Mental Retardation

Historical Perspectives on Mental Retardation Historically, prevailing sentiment was one of ignorance and mistreatment Degeneracy theory (1800’s) saw MR as regression to an earlier period in the development of humankind The eugenics movement (early 1900’s) led to the view that individuals with MR were threats to society

Intelligence and Adaptiveness Intelligence is conceptualized in terms of an “intelligence quotient” (IQ) MR is not defined solely on the basis of IQ; one’s level of adaptive functioning is important Adaptive functioning: how effectively an individual copes with ordinary life demands and how capable he/she is of living independently and abiding by community standards

IQ IQ is relatively stable over time, except when measured in young, normally-developing infants Mental ability is always modified by environment The Flynn Effect refers to the phenomenon that IQ scores have risen about 3 points per decade since IQ testing began Are IQ tests biased or unfair toward African Americans? African Americans score about 1 SD below whites likely due to economic and social inequality

Features of Mental Retardation DSM-IV Criteria significantly subaverage IQ (<70) concurrent deficits or impairments in adaptive functioning characteristics evident prior to age 18

Degrees of Impairment (DSM-IV) Mild MR (IQ of 55 to 70) applies to about 85% of persons with MR typically not identified until elementary school years overrepresentation of minority group members Moderate MR (IQ of 40 to 54) applies to about 10% of persons with MR usually identified during preschool years applies to many people with Down syndrome

Degrees of Impairment (cont.) Severe MR (IQ of 20 to 39) applies to about 3%-4% of persons with MR often associated with organic causes usually identified at a very young age Profound MR (IQ below 20 or 25) applies to about 1%-2% of persons with MR usually identified in infancy almost always associated with organic causes and often co-occurs with severe medical conditions

Level of Needed Supports AAMR bases categories on level of support or assistance needed (rather than on IQ): intermittent limited extensive pervasive Emphasis on interaction between person and environment in determining level of functioning

Prevalence 1-3% of population (depending on cutoff) Slightly more males than females More prevalent in lower SES and in minority groups, especially for mild MR; no differences for more severe levels

Prevalence (cont.) Figure 9.1 Factors accounting for differences in IQ scores between white and African-American children. Source: (Data from Brooks-Gunn, J., Klebanov, P. K., Smith, J., Duncan, G. J., & Lee, K. (2003). The Black-White test score gap in young children: Contributions of test and family characteristics. Applied Developmental Science, 7(4), pp. 239–252.)

Developmental Course Development vs. Difference Controversy Often children with mental retardation experience helplessness and frustration in their learning environments, which leads to low expectations and limited success With appropriate training and opportunities, children who have mild mental retardation may develop good adaptive skills in other domains

Language and Social Development Expressive language development may be weak in children with Down syndrome Fewer signals of distress or desire for proximity with primary caregiver, which can influence attachment Self-recognition often delayed, but positive Problems in the development of self-other understanding Deficits in social skills and social-cognitive ability; can lead to rejection by peers

Emotional and Behavioral Problems Emotional and behavioral disturbances four times greater than the general population Impulse control problems, anxiety problems, and mood problems common Internalizing problems in adolescence like normally-developing peers ADHD-related symptoms also common Pica and self-injurious behavior also common among those with severe and profound MR Lauren is a five-year old with Down syndrome. In the following video, her mother and her teacher discuss some of the emotional and behavioral challenges young children with Down syndrome experience in school

Other Disabilities Associated with MR Can be associated with other pervasive physical and developmental disabilities, including sensory impairments, cerebral palsy, and epilepsy Chance of other disability increases as degree of intellectual impairment increases

Other Disabilities Associated with MR (cont.) Figure 9.2 Physical disabilities among children with mental retardation. Data from C. C. Murphy et al., 1995.

Causes of Mental Retardation Many organic causes have been discovered but majority of cases cannot be explained, especially for mild mental retardation The two-group approach: organic mental retardation- includes chromosome abnormalities, single gene conditions, and neurobiological influences cultural-familial mental retardation- includes family history of mental retardation, economic deprivation, inadequate child care, poor nutrition, and parental psychopathology

Causes of Mental Retardation (cont.) Inheritance and the Role of the Environment heritability of intelligence is approximately 50% major environmental variations can affect cognitive performance in children from disadvantaged backgrounds prenatal influences may be mistaken for genetic when they are actually environmental

Causes of Mental Retardation (cont.) Figure 9.3 The approximate distribution of Stanford-Binet IQs. In practice, more children get low IQs than is predicted by this distribution. The excess of very low IQs has important implications for the two-group explanations of mental retardation—cultural-familial and organic. Source: Adapted from Understanding Mental Retardation, by E. Ziegler and R. J. Hodapp, p. 73. Copyright © 1986 by Cambridge University Press. Adapted by permission.Causes of Mental Retardation (cont.)

Causes of Mental Retardation Genetic and Constitutional Factors chromosomal abnormalities are the most common cause of severe MR Down syndrome due to an additional 21st chromosome Fragile-X syndrome, the most common cause of inherited MR, is associated with the FMR-1 gene Prader-Willi and Angelman syndromes both associated with abnormality of chromosome 15; believed to be spontaneous genetic birth defects occurring around the time of conception inborn errors of metabolism (referred to as single-gene conditions) can result in syndromes such as PKU

Causes of Mental Retardation (cont.) Neurobiological influences adverse biological conditions (e.g., malnutrition, exposure to toxins, prenatal and perinatal stressors) infections, traumas, and accidental poisonings during infancy and childhood prenatal alcohol exposure can lead to a Fetal Alcohol Spectrum Disorder (FASD) Social and Psychological influences deprivation of physical and emotional care and social stimulation particularly influential

Prevention, Education, Treatment Child’s overall adjustment is a function of parental participation, family resources, social supports, level of intellectual deficit, temperament, and other specific deficits Treatment involves a multi-component, integrated strategy that considers children’s needs within the context of their individual development, family and institutional setting, and community Prenatal education and screening may prevent some cases of MR

Prevention, Education, Treatment (cont.) Figure 9.4 Risk and protective factors affecting the psychological adjustment of intellectually disabled children (based on Lacharite et al., 1995).

Prevention, Education, Treatment (cont.) Psychosocial treatments intensive, child-focused, early intervention efforts are very promising (particularly for disadvantaged children) optimal timing for intervention is in the preschool years behavioral techniques include shaping, modeling, graduated guidance, and social skills training cognitive-behavioral techniques, such as self-instructional training and metacognitive training family oriented interventions help families cope with the demands of raising a child with MR